Pawl operating mechanism



April G. T. HARRIS 2,154,568

PAWL OPERATING MECHANISM Filed July 50,.1937 s Sheets-Sheet 1 t I WM;

G. T. HARRIS PAWL OPERATING MECHANISM April 18, 1939.

3 Shets-Sheet 2 Patented Apr.- 18, 1939 "PATENT orries 2,154,568 raw]. OPERATING MECHANISM ;-Garrcd new, Charleston, w. Va. Application July 30, 1931, Serial No. 156,590

8 Claims- (ci. 197-55) This invention relates generally to pawl and' ratchet mechanisms and more particularly to means adapted to be interposed between the pawl and pawl driving mechanism whereby motion of a predetermined character may be transmitted to the pawl. w

Although the invention is of general utility and application wherever it is desired to control the movement of a pawl and move the same at a 10' predetermined uniform or variable velocity, the invention has particular utility in connection with pawl and ratchet mechanism where the shaft or or other element to which the ratchet wheel is attached has a tendency to overrun due to the impetus imparted thereto during the driving stroke ofthe pawl. Thus/in conventional typewriter machines .where the platen is intermittently rotated by means of apawl and ratchet mechanism operated through a manually controlled lever, the platen is often rotated so rapidly and so suddenly that in instances where multiple copies are being typed, there is a marked tendency for the several sheets engagingthe platen to relatively shift and-thus bring the typed matter out of alignment. r

In present day typewriting machines it is common practice to provide a hand-operated lever .mounted on the carriage and by operation of which the carriage may be returned or back-' spaced as well as'the platen partially rotated. to

line space.

Usually the lever is arranged'so that it is given an initial rocking or pivotal movement to eflect line spacing and continued application of pressure :25 upon the levereffects back-spacing or carriage return. It has been found that these mechanisms possess an inherent characteristic which is objectionable in that it leads to defective operation when-the machine is being rapidlybperated by- 40 an experienced and fast operator. This objection arises due to the fact that the operator will give the lever a sharp, heavy blow suflicient to rapidly overcome the inertia of the relatively heavy carriage mechanism, and such blow, when communicated to the line spacingmechanism by the initial movement of said lever, causes relative slipping of the work in the machine particularly in cases where multiple carbons are being made; Th's slipping has been diagnosed by persons skilled in the artto be the result of the heavy,

sharp blow delivered to the line spacing lever by the operator in returning the carriage from left tofright, that it rotates theplaten in'line spac-- so yias to cause relative slippin f 55 apers in the machine due ,to the inertia thereof as above noted.

with respect to the driving force of the platen.

Furthermore,- it is well known among experienced typewriter operators that the continual shifting of the carriage by the hand operated lever usually provided on such machines, is an exceed- 5 ingly strenuous task when typing continuously throughout relatively long periods of time such as six to eight hours a day, as is common in general oflice practice.

With these facts in mind the invention seeks to provide means for relieving the operator of the necessity of taking her hand from the keyboard to shift the carriage from left to right andfor line spacing and to transfer this burden from the hand of the operator to the foot. Thus the operator is enabled to work more efllciently by having both hands on the keyboard at all times.

Another object of the invention is to provide a line spacing. mechanism including a pawl and ratchet drive for the pla -"n, which will preclude the possibility of slippage between papers in the machine due to operation of the line space lever Another object of the invention is to provide means for slowing down the motion of the line space lever to a degree suflicient to prevent relative slipping of the papers in the machine due to inertia when theplaten is rotated to line space.

Another object of the invention is to provide in an apparatus of the character indicated, means 'for adjusting the power transmission mechanism tov the foot of the'operator, and to detachably connect the same to the table or desk'on which f the typewriting machineis supported, by relatively simple and inexpensive mechanism.

. Another object of the invention is to provide in a treadle-operated cable transmission mechanism of the character described, a combined bracket and pulley unitwhich may be secured to a support by asingle hollow bolt member which functions 40 concurrently as a cable guide for the cable of the transr'nission mechanism.-

Another object of the invention is to provide motion transmission means' adapted to be interposed-between the pawl of a." pawl and ratchet 5 mechanism and the pawl dr'iving'mechanism for the purpose of transmitting to the pawl motion of predetermined character.

.These and other objects of the 'inventiongwill become apparent by a reading of the ifollcivqring specification taken in connection with the accompanying drawings, wherein I have illustrated a preferred form of my invention, but it is to be understood that various changes in details and combinations of partsas disclosed may bemade 5" without departing from the spirit of the invention as set forth more particularly in the appended claims.

In the accompanying drawings:

Figure 1 is a perspective view, partly in sec tion, of a typewriting machine having associated therewith the mechanism forming the subjectmatter of the present invention.

Fig. 2 is a plan view of the foot-operated treadle.

Fig. 3 is a side elevation of the treadle.

Fig. 4 is a vertical sectional view showing the pulley and supporting bracket therefor.

Fig. 5 is an elevation partly in section of the pulley bracket.

Fig. 6 is a detail view of the motion slow-down lever in its fully retracted position.

Fig. 7 is a perspective view of a slow-down lever and link for attachment to a slightly difierent form of typewriter from that shown in Fig. 1.

Fig. 8 is a further modified form of slow-down lever and link for a still different form of typewriter.

Fig. 9 is a diagrammatic view illustrating the broader aspects of my invention as applied to a simple pawl and ratchet mechanism.

Fig. 10 is a diagrammatic view showing my inventionapplied to a pawl and ratchet mechanism of the character wherein means are provided for adjusting the effective stroke of the pawl for moving the ratchet a greater or lesser amount,

as desired.

Fig. 11 is a diagrammatic view similar to that shown in Fig. 10 but slightly modified as to detail.

Referring more particularly to the accompanying drawings wherein like reference numerals are used to designate like parts throughout, I

have shown in Fig. 9 a ratchet wheel I5 mounted I upon a shaft I6 in a manner such that rotation of the ratchet wheel I5 will cause rotation of the shaft I8. The shaft I6 may be connected to any mechanism to be operated, such as the platen of a typewriting machine. A pawl I1 is pivotally mounted on the pawl arm I8 and said arm is pivotally supported at a convenient point such as upon the shaft I9, as shown. The pawl 11 is maintained in operative contact with the teeth of the ratchet wheel I5 by means of a suitable spring I9. The pawl and pawl arm are biased to a predetermined retracted position by means of the spring 88 connected between the pawl arm I8 and a pin 8I. Cooperating with the spring 88 is an abutment 82 positioned to define the normal or retracted position ofthe pawl. Any convenient means may be arranged to drive the pawl. In the present instance I have indicated a cable 83 which may be connected to any suitable source of power, such as a treadle mechanism as shown in Figs. 1 and 3. Interposed between the cable 83 and the pawl arm "I8 I provide mechanismior determining the character of motion to be transmitted to the pawl arm I8. This mechanism in the present embodiment of my invention, comprises a camplate 84 pivotally mounted at'88: on a suitable bracket or support 88, and having. an arcuate cam edge 81. The cam plate 84 is maintained in a normal retracted position against a extends beyond the cam plate 84 to provide a. pivotal mounting 9| for a bell crank lever generally indicated at '92. One arm 93 of the bell crank overlies the cam plate 84 and has the free end 94 pivotally connected to a link member 95,

the opposite endof which is pivotally connected to the pawl arm I8 at the point 96. The other arm 91 of the bell crank lever 92 is provided with a roller 98 arranged to bear against the cam edge 81 under the influence of the retractile spring 89 hereinbefore referred to. Thus, it will be seen that an intermittent pulling force applied to the cable 88 operates to rock the cam plate 84 about its pivot 88 against the tension of the return spring 89. The cam plate has the contour of the cam edge 81 designed to impart to the bell crank 92 through the roller 98 motion of a predetermined character which is transmitted through the bell crank and link 95 to the pawl and pawl arm 11, I8. It is apparentthat this arrangement provides definite means for delivering to the pawl arm I8 motion of adjustable or variable velocity-throughout a substantially infinite range of adjustment.

The mechanism shown in Fig. 9 is designed to give the same extent of movement to the ratchet wheel I8 and associated shaft I6 for each operation of the pawl; that is, regardless of the character of the motion transmitted to the pawl, the pawl is effective for one operative stroke to move the ratchet and associated shaft a given amount.

In Fig. 10 I have shown a modified form of pawl and ratchet mechanism embodying my invention wherein means are provided for adjusting the throw of the pawl throughout a range of one, two or three ratchet teeth. One form of adjustment comprises a pawl restraining camplate 99 pivotally mounted upon a shaft I9 and having a cam portion I89 disposed substantially parallel to the axis of shaft I8 and interposed between the teeth of the ratchet wheel I5 and the pawl 11. Thus, the pawl biasing spring I9 tends to maintain the nose of the pawl in contact with the hold-out cam I99. It willbe noted that the cam I88 has an arcuate or angular extent substantially equal to the width of two ratchet teeth. Thus, in the position shown in Fig. 18 with the nose of the pawl 'I'I resting adjacent the left hand edge of said cam portion, the pawl in its first increment of movement under the driving impulse of the cable 88, drops into operative engagement with the ratchet tooth IM to move the ratchet wheel I5 throughout the entire range of driving movement ofthe pawl arm I8, which in the present in- I stance is the space of three ratchet teeth, as in- 'dicated by the numeral 8 on the indicia plate 1 I82 with which a suitable pointer I88 carried by the'cam plate 99 cooperates. If the cam plate be shifted in a counterclockwise direction to bringthe pointer I98v into alignment with the numeral 2 on the indicia plate I92, the nose of?" the pawl II will lie substantially midway between the ends of the cam portion I98 with the pawl in the retracted position shown in Fig. '18. Thus, for an operating impulse on the cable 83 the pawl 11 will, for theflrst increment of its driving movement, ride upon the surface of said cam portion I98. during which movement it isineifective to drive the ratchet wheel I5. The parts of the mechanism are designed so that this increment of pawl movement is substantially equivalent to the space of one ratchet tooth so that when the pawl drops into operative engagement with the teeth of the ratchet there remains an increment of driving movement substantially arc isstruck from the pivot point 98 upon the lever 18 with said lever moved counterclockwise .of the apparatus the ratchet wheel 15 is driven -two spaces.

Similarly, if the cam plate 99 is moved to bring the. pointer I03 in alignment with the numeral I on the indicia plate I02, the pawl 11 is maintained ineifective for the space of two ratchet teeth so that it delivers a driving impulse to the ratchet wheel 15 equivalent to substantially one ratchet tooth only.

In the arrangement just described it is apparent that so long as the pointer I03 is in the position shown, full advantage of the contour of cam plate 84 may be realized in controlling or modifying the movement of pawl 11 and pawl arm 18. However, when the pointer I03 is shifted to either No. 1 or No; 2 positions as indicated by the scale I02, the pawl I01 must ride a greater or lesser extent upon the surface of the cam' I before dropping into operative engagementwith the teeth of the ratchet 15. Thisis objectionable in some instances in that full benefit of the cam contour is not realized. This feature, however, is

I remedied by theprovision of a plurality of apertures in the arm 93 of the bell crank lever 92 by which the link 95 may be connected to said am in a plurality of positions. These apertures are indicated in Fig. 10 by the reference numerals 104 -104 and 104. The respective locations of these apertures on the lever arm 93. are ob- .tained in the following manner: With the pawl arm 18 in its fully retracted position against the abutment 82, and with the cam plate 84 and bell crank lever 92 in their normal or fully retracted position, an arc is struck about the pivot point 96 on the pawl arm "through the center of the bell crank pivot 9I. The cam plate 94 is now moved substantially 90 into the dotted line position shown in Fig. and with the bell crank 92 in its fully displaced position, also indicated indotted lines, an arc intersecting the first drawn a distance such as to move. the ratchet wheel a distance corresponding to three full teeth, or

such as shown in' dotted lines in Fig. 10. The

point of intersection between these two arcs determines the location of the aperture I04. The apertures I04 and H14' are similarly located by striking arcs intersecting the first drawn arc from the pivot point 96 with the pawl arm 18 successively moved counterclockwise a distance corresponding to movement of the ratchet 15 a distance of, two teeth and one tooth, respectively; l

- It is to-be noted in this connection that the cam' plate 94 has an efiective arcuate extent cooperable with the roller '98 of the bell crank 92 of substantially 90. designed so that the first increment of angular or pivotal movement of the plate 84 is utilized for moving the pawl 11 from its retracted position on the hold-out'cam surface I00 to a' position operatively engaging the ratchet tooth IN and the remainderof the contour of cam plate .84 is fashioned and utilized for the purpose of modifying and controlling the eifective movement of the pawl. It will be realized that by determining i the location of the connecting aperture's- I04 I04, I04 in the manner described, the movement of the pawl effective tomove the'ratchet 15 one,

two or three toothspaces, may be readily accomplished by connecting the link 95 to the lever 93 in the desired'aperture. By having all of the apertures I04, I04 and "4" located on an arc aboutthe pivot 96 with the pawl in .its fully reabutment I82. The contour of the cam is,

lines in Fig. 11.

tracted position, said pawl may assume such teeth dependingupon the connection of the link 95 in apertures I04, I04 and I04, respectively. It is also to be noted that in the arrangement just described the same major portion of the contour of cam plate 84 is utilized for moving the pawl 11 irrespective of the point of connection between the link 95 and the lever arm 93. This feature provides means for definitely controlling or modifying the motion communicated to the pawl in all positions of adjustment of the link 95.

I have shown in Fig. 11 a further modification of my invention by which substantially the full contour of. the cam 84 may be utilized for controlling or modifying the movement of the pawl.

Generally speaking, this modification differs from ment of the pawl is, terminated at the same point for all positions of adjustment of the link 95,

whereas in the modification shown in Fig. 10 .the arrangement is such that the pawl starts.

from the same point in all positions ofadjustment of the link 95 but terminates at diflerent positions depending upon the'degree of operative throw of the pawl desired.

Referring more particularly to Fig. 11, I provide an abutment l82-adjacent the periphery of the ratchet wheel I15 and in the path of movement of the pawl I11. The pawl I11 and the abutment I82 are designed to cooperate to terminate the efiective movement of the pawl and to that shown in Fig. 10 in that the effective movecorrespondingly due to the engagement of theroller I98 with the contour of the cam 84, an arc is struck through the center of the pivot l-9I from the point "I96 on the pawl arm I18 when said arm is in the position such that the nose I11 of the pawl "-1 is in engagement with the abutment I82. The are so drawn will deter? mine the general location of the points ofconnection for the lever I95 on the arm I93 to terminate the efiective movement of the pawl at the To determine the actual point of location on the arm of the apertures by which the link is connected thereto, the pawl arm I18 is moved-from the dotted line position in which the pawl is in engagement withthe abutment 182 clockwise distances corresponding respecthrough the first struck arc with the lever I92 and the' cam plate I94 in a position displaced substantially 30 degrees from that shown. in full purely arbitrary and can be increased or dimin- The '30 de ees mentioned is tively to one, two-and three ratchet teeth, and from these positions-intersecting arcs are struck ished accordi to the requirements of a given application, it being noted that this initial increment of movement of the can? plate 84 is uti lized for moving the pawl I11 from its position of engagement with the hold-out cam 200 into operative engagement with the first ratchet tooth 2|II. It will also be understood that in this modification 01' my invention it is necessary to shift the hold-out cam 208 to bring the pointer 283 into alignment with the proper indicia on the plate I82 for each position of adjustment of the link I95 on the arm I93, since the points of connection on said lever arm I93 are located in a manner such as to draw the pawl arm I18 in a counterclockwise direction as the eccentricity of the point of connection is reduced;

The connection between the link 95 and arm 93 and between the link I 95 and the arm I93 may be any desired type of quick-detachable connection which will facilitate shifting the point of connection of the link to the desired aperture in the lever arm.

, In both forms of my invention shown in Figs. 10 and 11 it will-be noted that I arbitrarily uti-' lize a small angular extent of the contour of the cam plates 84 for moving the pawl from its inoperative position in engagement with the holdout cam into operative engagement with the first ratchet tooth. Also, this initial increment of cam contour is designed to have but a slight degree of eccentricity with respect to the pivot of the cam plate so that the pawl is slowly moved into engagement with the first ratchet tooth. This avoids all possibility of shock due to impact between the pawl and ratchet tooth and thereby avoids the possibility of slippage between the shaft I6 and any means or element which is triotionally driven therefrom, such as the papers in a typewritlng machine where the shaft 16 carries the platen of such machine.

It is also to be noted in connection with the form of my invention shown in Fig. 10 that, due to the variable eccentricity of the points of connection between the link 95 and the lever. 93, therewill be a slight variation in the actual point of contact between the roller 98 and the cam plate 94 when the pawl 11 actually engages the ratchet tooth IOI. This variation is, however, so slight as to be entirely negligible in the operation of the invention as described. Similarly, in the modification shown in Fig. 11, the variable eccentricity of the point of connection between the link I95 and the lever arm I93 will aifect the actual point of contact between the pawl I11 and hold-out cam surface 299 in the normal or retracted position of the pawl for the different adjustments of the link I95. Here again, however, the variation is so slight as to be entirely negligible in controlling or modifying the movement of the pawl.

Referring now to Fig. 1, I have shown my invention applied to a well known form of typewriter in wide use today, and, which employs a combined line space and carriage return lever indicatedgenerally by the reference character I. The lever I is pivoted at 2 to a portion of the typewriter carriage mechanism 3 and is connected by link 4 to the platen rotating pawl and ratchet mechanism 55a. Thus, in operation, the operator by striking the outer end of the lever I, rocks the same about its pivot 2 to actuextremely enervating, and due to the inherent characteristics of such mechanism, results in relative slipping of sheets of work in the machine due to the rapidity with which the platen is rotated when struck by the operator in the normal course of return of the carriage from left to right. It is understood thatthe mechanism thus far referred to is an integral part of the typewriter machines as purchased and forms no part of the present invention.

My invention may readily be designed as an attachment for machines of the type hereinbefore referred to, and which will relieve the operator of the necessity of line spacing and returning the carriage to the right by ,hand, and includes an attachment which may be readily mounted on the machine and-not affect the otherwise normal operation thereof. Thus, my invention contemplates a bracket member 8 which may be secured to the carriage of the machine'in any suitable manner. In the form of machine shown" in Fig. 1 the bracket may conveniently be secured to the rear left side of the machine, as viewed from the operators position, by means of a screw and nut provided on the machine to secure parts thereof together. Thus the nut 9 normally employed for securing the end of the rod ID to the end of the carriage, may be removed and likewise the screw or bolt II also employed for securing the part of the machine to the carriage and plate is removed, and

the bracket 8 having a suitably apertured upstanding wing portion I2, is then fitted over the projecting end of the rod I8 with an aperture in alignment with the hole in the carriage end plate for the bolt II, after which the bolt II and the nut 9 are replaced in their proper position and the bracket 8 is thus securely fastened to the end plate I3 projecting beyond the cam plate 84,-

with the roller 98 carried at the free end of the arm 91 of said lever bearing against the cam edge 81 of the plate 84. The opposite arm 93 of the bell crank 92 is provided with the spaced apertures I94 for connection with the link 95, as shown, the opposite end of said link being connected to the pivotal connection I8 between the lever I and the pawl driving link 4. By this arrangement it is apparent that the pivotal movement of the plate 84 is communicated to the bell crank 92 through the cam edge 81 and as modified thereby, is delivered .to the pawl mechanism 5, 5a in the mannerllereinbefore described in connection with the modifications shown in Figs. 9, 10 and 11. 7

While 'I may employ'either the modification shown in Fig. 10 or 11, I prefer, for use in typewriter mechanism, to employ thatshown in Fig. 11, since it definitely precludes any variation in spacing of the platen due to wear of the pivot links, etc., inasmuch as the'eflective movement of the pawl transmitted to the ratchet is defiarc-goes g iltely'lpredetermined by the abutment I82 of g.

My invention contemplates actuation of the cam plate 84 by means of a foot operated instruas shown in Fig. 3, said portions depending from the foot portion of the treadle. The wing portions 24 are provided with one or more apertures 25 to receive a fulcrum pin 28, the latter passing through the upstanding flanges 23 of the frame member and through aligned apertures 25in the ranged to be adjustably secured to wing portions 24 of the treadle. By this arrangement the treadle member is pivotally mounted in the frame member 28 and may be readily adjustable fore and aft. with respect to the frame and pivot member 28 for the purpose of properly balancing and proportioning the pedal to the sizeof the operators foot and the normal range of pivotal movement thereof provided at the ankle joint. At the toe portion of the treadle I9 I provide an overhanging bracket member 21 havin an end portion 28 disposed above the toe portion of .the lever l9 and provided with a plurality of apertures 29 by which a cable member 38 may be. adjustably secured thereto. It will be understood that the cable 38 may be secured to the bracket 21 in any one of the apertures 29 and thus provide means for properly proportioning the lever action of the treadle |9 to the strength of the operator.-

The cable 38 passes upwardly from the bracket 21 through a hollow bolt and guide member 3| by which'a pulley supporting bracket 32 is secured to the top of the desk or table-22. Asshown in Figs. 4 and 5, the pulley and bracket assembly includes the bracket member 32 which is formed with a substantially horizontal foot portion 33 and an upstanding bracket portion 34. The foot portion 33 is apertured for alignment withv an aperture in the member 32 may be conveniently secured to the table top by means of the hollow bolt member 3|, the latter serving simultaneously as a guide for the cable 38 and as means for securing the bracket to the table. Projecting laterally from the bracket portion 34 of the bracket and pulley assembly is a stub shaft 35 upon which a double pulley comprising a large pulley 36 and a'small pulley 31 is which is attached to the bracket 21 of the treadle,

has its. opposite end wound about the small pul-' ley and secured thereto as at 38. The large pulley 38 has wound thereabout a secondcable 39', the end of which is secured to the pulley as at 39. The dual pulley unit 36, 31 is housed within a suitable casing 40 which is secured to the bracket member 34 by means of a plate member 4| which is engaged over the threaded end 42 of the stub shaft 35 and secured thereto by any suitable means such as the nut 43. As shown in Fig. 4, the casing member 48 is suitably apertured as at 44 and 45 to permit free passage of' the cables 30 and 30'; respectively,.therethrough.

- It is further to be noted that, the frame member 20 which supports the foot treadle I8 is arthe legs 2| of the bench or writing machine is mounted. Thus, the frame 28 28 provided with a generally upstandtable top 22 so that the bracket mounted. The cable 38, one end of table 22 upon which the typef tending .in divergent relation therefrom. The

strap members 18 are provided at their free extremities with fastening elements 1| designed to be wrapped about the lower portion of the legs 2| and thus secure the frame in fixed position thereto. The straps 10 being thus securely tied 'to the legs 2| prevent shifting or lateral movement of the frame. member 28 during operation of the pedal |9 by the foot of the operator. Due to the manner of securing the straps 18 to the frame 20, said straps may be adjusted angularly with respect thereto in order to accommodate the apparatus to tables in which the legs are a greater or lesser distance apart. Referenceis here made to the single'securing element 12 by which the straps are secured frame 28. It is also to be noted that by the provision of a plurality of apertures in the horizontal plane of the frame 29 for said securing elements 12, the entire pedal unit aft to a proper position of adjustment for any operator.

Referring to Fig. 1, the pulley and bracket assembly 32 is shown provided with an upstanding I pulley supporting arm 48 at theupper end of which is pivotally mounted a guide pulley 41; The cable 39 is led from the pulley casing 40 through the aperture 44 and is thence trained around the pulley 41 and carried transversely across the back of the typewriting machine and attached to a laterally projecting arm 48 provided on the plate 84.

The upstanding portion |2 of the bracket 8 is designed to cooperate with the flattened abutment portion 58 of the cam plate 84 to limit the extent of pivotal movement of said cam plate through an arc of substantially 90 degrees, as shown more clearly in Fig. 6. It will be understood that when the parts have reached the position shown in Fig. 6 continuedpullon the cable 30' is eifective to move the carriage from left to right. In order to relieve the bracket securing means 9 and H and the upstanding portion |2 of the bracket from undue strain during this shifting movement-of the carriage, the horizontal portion |3 of the bracket is extended transversely of the carriage and'embraces the eccentric stop .pin 1, as clearly shown in Fig. 1.

In conventional typewriting machines of the type disclosed in Fig. 1 there are provided spring biasing 'means for maintaining-the pawl mechanism 5 and thev associated operating lever in a normal-retracted position.- This spring mechanism (not show) is sufiicient to maintain the roller 98 of the bell crank lever 92 in operative engagement with the cam edge 81 of the plate 84. The plate 84 is biased to the position shown in Fig. 1 by the spring means 89 previously described in connection with Figs; 9 and 10 and in the arrangement shown in Fig. 1 this spring is also instrumental in elevating the treadle -|9 when pressure thereon is removed. Obviouslythe spring 89 may be supplemented by additional spring biasing means associated with either the treadle l8 or the pulley unit 32.

In operation, the operator, when the carriage has reached the extreme left hand position of 1 and 2 is provided with suitable to the lower flange of the may be shifted fore and the machine as a result of having completed a 6 of force on the pedal is operates through the cables 38 and 88', cam plate 84 and stop member 58, to move the entire carriage mechanism to the right hand side of the machine. Upon release of pressure on the treadle It by the foot of the operator, the spring instrumentality associated with the lever I, will retract the pawl driving mechanism 4, 5 to its normal position and through the instrumentality of the link 15, the lever 92 is simultaneously retracted, The treadle l9 and plate 84 will be returned to normal position by spring 89. Due to the various adnected to a bracket 8| sition further relieves the iustments provided in the motion transmission mechanism between the treadle l9 and the pawl driving mechanism 4, 5, the treadle l8 selectively operated to give line spacing without back spacing or successive line spacing and back spacing. Furthermor due to the motion modifying cam plate 84 included in the power transmission mechanism just referred to, it is possible to line space withthe platen braking detent mechanism in inoperative position,and without any overrun or overthrow of the platen. The detent mechanism here referred to is that normally provided on machines of the type and through the instrumentallty of which the rotary movement of the platenis checked. o'r

braked, and on the present machine is cdntrolled by the lever indicated at 5|. This provision of means for line spacing accurately withthe controlling detent mechanism in inoperative pooperator of a burden in that the drag. of the platen due to the line spacing detent maybe entirely dispensed with and the platen accurately driven.

The line spacing adjustment mechanism provided in machines of the type illustrated in Fig. l is shown at I88 and by properly positioning this lever in accordance with a calibrated scale, not shown, but similar to that shown at I82 in Fig. 10, the pawl and ratchet mechanism 8-841 may be controlled to insure the platen being moved one, two or three spaces, as desired.

In Figs. 7 and 8 I have shown simplified modifications of my invention by which the motion transmitted to the pawl and ratchet mechanism by the cable attached to the treadle mechanism may be modified to the extent that the motion of the treadle is appreciably slowed down, thus insuring a minimum impact between the pawl and associated ratchet. Thus, in Fig. 7 an attaching bracket 82 has a depending portion 83 arranged to position the horizontal portion 84 ofthe bracket at a level below the attaching portion of the bracket. The horizontal portion 84 has pivotally connected thereto at the point 59, a lever 85 which is connected by means of a link 58 with the pawl and ratchet operating means of a machine of slightly difl'erent form than that shown in Fig. 1. The operating cable may be attached to the lever 55 at the point 88. One or more apertures 81 may be provided for adjustably connecting the link 88 to the bracket 85.

In Fig. 8a lever 88 is shown pivotally conby the pivot screw 82. A link 88 is pivotally connected to the lever 88 at point 84, said lever being designed for connection to a pawl type illustrated on the machine in Fig. 1. Thus, the free end 85'01' the link is designed for connection to the pivot screw ll of the machine of Fig.1. A spring member 88 has its opposite ends connected to the lever 88 and an arm 81 of the may beand ratchet mechanism of the purpose of biasing the lever 88 to normal position, such as shown in Fig. 8.

lever 88 for the its Both of the simplified forms of my invention as shown in Figs. 7 and 8 are characterized by a peculiar disposition of pivotal connections between the link and lever and between the lever and bracket. This connection is such that the initial movement of the link, by reason of rocking movement of the lever, is substantially parallel to the line of movement of the pawl, whereas during the final increment of pivotal movement of the levers, the point of connection between the link and lever moves substantially transversely to the line of movement of the pawl so that during the latter stages of rocking movements of the lever, substantially little motion is imparted to the pawl. This result obtains from the relative disposition of the point of connection between the link and lever with respect to the pivotal axis of being so arranged that the point of connection between the link and lever moves behind the pivotal axis of the lever during the final stages of pivotal movement of said lever.

In conclusion, it is apparent in view of the foregoing description and, illustration in the acv companying drawings,

tion transmission means adapted to be interposed between a pawl and the means for driving it, whereby motion of any be imparted to said pawl. Furthermore, I have provided a foot treadle operated mechanism for eifecting line spacing and carriage return operation for conventional typewriter machines and n a form such that the mechanism may be readily attached to typewriters of conventional form with a minimum of time and without the necessity of drilling or otherwise modifying the conventional typewriter machine to accommoldate it to the mechanism forming the subjectmatter of my invention. Furthermore, due to.

the va ious adjustments provided in the power transm on mechanism between the treadle and the platen driving pawl, it is possible to line space independently of back space or carriage return operations. It is also possible to accurately line space with my improved mechanism with the platen braking detent mechanism in inoperative position. This relieves the operator of the weight of drag of this brake mechanism and thereby lessens the labor entailed in operating the machine.

It is further to be noted that one form oi the invention is characterized fying cam plate, the contour of which may be designed to impart any desired type of motion to the pawl, such as shown in 10, whereas anotherform of characterized by a link and lever mechanism for communicating motion of a foot pedal to the pawl and ratchet mechanism which drives the platen, and in which the connection between the link and lever is such that in the normal position of the parts the point of connection lies laterally of an imaginary line passing through the pivot of the slow-down lever and the pivot of the line spacing lever supplied with the machine,so that as the slow-down lever is rocked by operation of the foot pedal, said point of connection moves in the arc of a circle about the pivot of said slow-down lever with the result that during the final increment of movement of said lever, said point of connection is moving substantially transverse to the general line of movement of the link with respect to the pawl Figs. 1, 6, 9 and my invention is that I have provided mo-- desired character may go by a motion modiwhich drives the platen. This construction precludes the possibility of overrun of the platen shown without departing from. the spirit of. my,

invention, the important and novel features of which are set forth more in detail in the following claims;

Having thus described my invention, what I claim as new is: Y

1. In a typewriting machine including a' ro-. tatable platen, pawl and-ratchet mechanism for intermittently drivingthe platen to effect line spacing, a pivoted lever, operator operated means for operating said lever, and linkage connecting said lever and said, pawl, the point of connection between the linkage and said lever being such that during the initial movement -o1! said lever said point of connection moves substantially parallel to theline of movementof the pawl, and in the final stages of movement of said leversaid point of connection moves in a direction substantially transverse to the line of movement of the pawl.

v2; In a typewriting machine including a rotatable -platen, a pawl for driving 'the platen and a lever for actuating the pawl, the combination with said lever of a second lever, means for pivotally mounting said second lever on said typewriting machine, a link connecting said levers, the point of connection-between said link and said second lever being eccentrically disposed with respect to the pivotal axis of said second lever an amount substantially equal to the operative range of movement of the pawl,

pivotally mounted actuating means for said second-mentioned lever, and means for limiting the pivotal movement of said actuating means to substantially ninety degrees.

.3. In. a typewriting machine including a rotatable platen, a pawl for driving the platen and a lever for actuating the pawl, the combination with said lever of a second lever, means for pivotally mounting said second lever on said typewriting machine, a link connecting said levers, the point of connection between said link and said second lever being eccentrically disposed with respect to the pivotal axis of said second lever an amount substantially equal to the operative. range of movement of the pawl, pivotally mounted actuating means for said second-mentioned lever, means forlimiting the pivotal movement of said actuating means to substantially ninety degrees, and means included in said typewriting machine for maintaining said pawl in retracted position and said second lever in a position such that the point of connection between said lever and link is disposed laterally of an imaginary line passing through the pivotal axes of said first and second levers, and. means for moving said pivotally mounted actuating means about its pivot through substantially ninety degrees, whereby said point of connec- I ,tion between the link and said second levermoves to a point substantially within said imaginary line. 1

4.1m attachment for typewriting machines including a carriage, a rotatable platen carried by the carriage, a pawl for driving the'platen,

and a lever, for actuating the pawl; said attach ment comprising a bracket member secured to the frame of the. carriage, an outstanding arm carried by the bracket, a-lever pivotally supported on said am, a link connected between said last-mentioned lever and said first-menated means foractuating said second mentioned lever, for actuating the pawl, and stop means for limiting the pivotal movement of said pivotally mounted actuating means to substantially" ninety degrees, the link, said second mentioned lever," and said pivotally mounted actuating means being designed and proportioned to reduce the speed of the first mentioned lever, during the final increments of pivotal movement thereof, in response to substantially uniform speed of operation of the pivotally mounted actuating means. I

5. In a typewriting machine including a shiftable carriage having a rotatable platen mounttionedlever, pivotally mounted operator opered thereon, pawl and ratchet mechanism forintermittently rotating the platen to effect line spacing, and means including an operator operated lever. for driving the pawl and subsequently laterally shifting the carriage, the combination with said pawl and lever of motion modifying means interposed therebetween,. said motion modifying means including a cam having a control contour of predetermined design and means for communicating the motion of the Tever modified in accordance with the cam contour to the pawl whereby to rotate the platen without overrun, said motion modifying means also including means for subsequently shifting.

the carriage at full speed.

6. In a typewriting machine including a shiftable carriage, a platen rotatably mounted on the carriage, and pawl and ratchet mechanism for intermittently rotating the platen, the combination of an actuator member, motion trans-' mission means operatively connecting the actuator member with said carriage and withsaid .pawl for rotating the platen and then shifting the carriage when the actuator member is actuated, said motion transmission means including means for converting the movement of theactuator member into motion of non-uniform velocity of the pawl torotate the platen without dangerof overrun, said non-uniform velocity motion being characterized by an increment of relatively rapid movement of the pawl followed by an increment of relatively slow movement, of the pawl whereby to rotate the platen quickly but without overrun, and means to shift the carriage at the speed'of the actuator member,

'7. In a typewriting machine a transversely movable carriage, a platen rotatably mounted thereon, a lever pivotally mounted on the carriage, pawl and ratchet mechanism actuated by the lever to rotate the platen, a cam member pivotally mounted on the carriage, said camoperatively engaging said lever, cam actuating means including an actuator member fixed with respect to the typewriting machine, connection means between said actuating member and said cam, means biasing the cam to a predetermined normal position and stop means limiting the extent of pivotal movement ofvv the caminresponse to operation of said actuating member whereby operation of the actuating member first causes rotation of the platen and then shifts said carriage upon engagement of the cam with said stop means. v

8. In a pawl and ratchet mechanism a ratchet member-mounted for rotation, a pawl for intermittently driving the ratchet member, means for movably-mounting the pawl in operative relation substantially parallel to the path of movement of the pawl during the initial stages of movement of the pawl and to move transversely of the path of movement of the pawl during the final stages of movement thereof.

GARRED T. HARRIS. 

